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Mom, Dad… There’s something you need to know… I’m a MAMMAL!. Origin of Species Chpt. 24. “That mystery of mysteries…”. Darwin never actually tackled how new species arose….

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slide1

Mom, Dad…

There’s something you need to know…

I’m a MAMMAL!

Origin of Species

Chpt. 24

slide2

“That mystery of mysteries…”

Darwin never actually tackled how new species arose…

Both in space and time, we seem to be brought somewhat near to that great fact—thatmystery ofmysteries—the first appearance of new beings on this Earth.

slide3

origin of new taxonomic groups

Macroevolution macroevoluti macroevolu macroevo

slide4

origin of new species

speciation

speciati

specia

spec

slide5

HOW??

speciation - origin of a new speciesKEYTO MACROEVOLUTION!!

slide6

Anagenesis= one species transforming into oneother species

Nobiologicaldiversity created

speciation= origin of a new species

slide7

Cladogenesis= one species transforming into more species

Biological diversity created

speciation=origin of a new species

slide9

SPECIES

potential to interbreed

produce viable offspring

slide10

So…what is a species?

  • Biological species concept
    • defined by Ernst Mayr
    • population whose members can interbreed & produce viable, fertile offspring
    • reproductively compatible

Distinct species:songs & behaviors are different enough to prevent interbreeding

Eastern Meadowlark

Western Meadowlark

slide11

Question

How many species of African Violets are here?

SPECIES

slide14

Prezygotic

Barriers

slide17

allopatric

    • geographic separation
slide19

Temporal isolation

  • Species that breed during different times of day, different seasons, or different years cannot mix gametes
    • sympatric
      • reproductive separation

Eastern spotted skunk (L) & western spotted skunk (R) overlap in range but eastern mates in late winter & western mates in late summer

slide20

What factors isolate gene pools?

Blue footed boobies mate only after a courtship display unique to their species

Behavioral Isolation

  • reproductive isolation
slide21

What factors isolate gene pools?

Behavioral Isolation

  • reproductive isolation
slide22

What factors isolate gene pools?

sympatric speciation?

Even in closely related species of plants, the flowers often have distinct appearances that attract different pollinators. These 2 species of monkey flower differ greatly in shape & color, therefore cross-pollination does not happen.

Mechanical Isolation

Plants

slide23

What factors isolate gene pools?

sympatric speciation?

Animals

  • For many insects, male & female sex organs of closely related species do not fit together, preventing sperm transfer
    • lack of “fit” between sexual organs: hard to imagine for us… but a big issue for insects with different shaped genitals!

Mechanical Isolation

slide24

What factors isolate gene pools?

sympatric speciation

Gametic Isolation

slide25

Gametic isolation

  • Sperm of one species may not be able to fertilize eggs of another species
    • mechanisms
      • biochemical barrier so sperm cannot penetrate egg
        • receptor recognition: lock & key between egg & sperm
      • chemical incompatibility
        • sperm cannot survive in female reproductive tract

Sea urchins release sperm & eggs into surrounding waters where they fuse & form zygotes. Gametes of different species— red & purple —are unable to fuse.

slide26

PostZygotic

Barriers

slide27

What factors isolate gene pools?

Reduced Hybrid Viability

slide28

What factors isolate gene pools?

Reduced Hybrid Fertility

ex. mules

slide29

Reduced hybrid fertility

  • Even if hybrids are vigorous they may be sterile
    • chromosomes of parents may differ in number or structure & meiosis in hybrids may fail to produce normal gametes

Mules are vigorous, but sterile

Horses have 64 chromosomes

(32 pairs)

Donkeys have 62 chromosomes

(31 pairs)

Mules have 63 chromosomes!

slide30

What factors isolate gene pools?

Hybrid breakdown

F1 fine, subsequent… no good

slide31

Hybrid breakdown

sympatric speciation?

  • Hybrids may be fertile & viable in first generation, but when they mate offspring are feeble or sterile

In strains of cultivated rice, hybrids are vigorous but plants in next generation are small & sterile.

On path to separate species.

slide34

=AllopatricSpeciation

ex. Adaptive radiation

slide41

Polyploidy

2N 4N

=SympatricSpeciation

TEMPO of evolution

slide42

BIG changes occur b/c of the accumulation of small changes

  • Polyploidy

2N 4N

=SympatricSpeciation

GRADUALISM

slide43

Polyploidy

2N 4N

=SympatricSpeciation

TEMPO of evolution

slide44

Polyploidy

2N 4N

=SympatricSpeciation

Big changes as it “buds” from parent species, few changes after that

Stephen J. Gould – 1972

slide46

change in rate & timing of developmental events in various parts of the body

how did we differentiate

????????

slide47

change in rate & timing of developmental events in various parts of the body

how did we differentiate????????

If these genes are altered, the timing of development and rate will be altered within the species

slide48

change in rate & timing of developmental events in various parts of the body

how did we differentiate????????

If these genes are altered, the timing of development and rate will be altered within the species

slide49

Hox Genes

1983 -Dr. Thomas Kaufman - Indiana University discovered

Clusters of genes, involved in the regulation of development of animals, plants, fungi

slide50

Hox

Genes

Evolved in the paleozoic era

slide51

Hox Genes

If mutated… OOPS

slide53

Hox Genes

Clusters of genes, that determine where limbs and other body segments will grow in a developing fetus or larva

slide54

Hox Genes

When these genes are altered, positioning varies

Clusters of genes, provide positional info in the embryo

slide55

Hox Genes

When these genes are altered, positioning varies

Clusters of genes, provide positional info in the embryo

slide56

So, if we are connected, how did we differentiate???

Evolution is not the survival of the fittest. Rather it is the survival of the just good enough.

what drove human evolution
What drove Human Evolution?

http://www.npr.org/templates/story/story.php?storyId=124906102

slide58

Summary

  • Be able to discuss the main theories of what is a “species”.
  • Know various reproductive barriers and examples.
slide59

Summary

  • Know allopatric and sympatric speciation.
  • Be able to discuss gradualism and punctuated equilibrium theories.
slide60

Summary

Recognize various ideas about the origin of evolutionary novelties.

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